In general, an elevator system includes a plurality of door interlocks installed on landing doors at their respective landing floors. These door interlocks are configured to be released by mechanically interlocking with an elevator car door when the elevator car door is open on arrival of the elevator car at their respective landing floors. With such a configuration, not only can landing doors at the landing floors be prevented from being opened improperly from the outside, but the operation of the elevator car can be interrupted appropriately even if a landing door was opened, thereby unforeseen accidents can be avoided in advance.
Such a door interlock is usually provided with a landing door switch for detecting a locked state and an unlocked state of the door interlock, and a switch contact of the landing door switch is opened and closed in conjunction with the opening and closing of the door interlock. Each landing door switch is connected in series with each other and with a relay coil of a door close detection relay. The door close detection relay is configured such that a relay contact of the door close detection relay is closed only when all the landing door switches are closed, followed by sending a signal indicative of the closed state of all the door switches to the elevator control device to properly operate the elevator car.
On the other hand, in such a landing door switch, it is known that a poor contact may occur due to dust adhesions to a switch contact, contact corrosions, aged deteriorations, etc. In a case when a periodical inspection is performed, a maintenance person has to inspect all the door interlocks manually (and the landing door switches as well). In particular, when the elevator system is installed in a high-rise building, the number of door interlocks to be checked increases and it takes more time for inspection, and thus there is a disadvantage of increasing a burden on the maintenance person.
Furthermore, even if there is a poor contact in only one of the landing door switches, it is not only necessary to examine all of the door interlocks (and the landing door switches accordingly), but is necessary to identify whether a specific door interlock itself is in an abnormal condition or a lading door switch has a contact failure. In such a case, it requires much more time to recover the entire elevator system.
Therefore, there exists in the art a need for providing a door switch inspection device, capable of not only detecting abnormal conditions in a landing door switch, but also identifying on which landing door switch a poor electrical contact occurs in advance of failure.